WO2019012924A1

WO2019012924A1 - Heavy-duty tire

Info

Publication number: WO2019012924A1
Application number: PCT/JP2018/023284
Authority: WO
Inventors: 章史佐藤
Original assignee: 株式会社ブリヂストン
Priority date: 2017-07-11
Filing date: 2018-06-19
Publication date: 2019-01-17
Also published as: US20200207159A1; JPWO2019012924A1; CN110785298A; EP3653405A1; JP6966548B2; EP3653405A4

Abstract

The chafer (100) of this heavy-duty tire (10) is provided between a bead core (61) and a carcass (40) and is formed from organic fiber. (L1/L2)≤(5/12) is satisfied where: L1 is the linear distance between a bead innermost position (61p), which is the innermost point on the bead core (61) in the tire width direction, and the outer end (100a) of the chafer 100 in the tire radial direction; and L2 is the linear distance between the bead innermost position (61p) and a carcass outermost position (40p), which is the outermost point on a carcass body portion (42) in the tire width direction.

Description

Heavy duty tire

The present invention relates to a heavy duty tire provided with a chafer covering at least a part of a bead portion.

Heavy duty tires mounted on vehicles that are loaded with high loads such as construction vehicles and industrial vehicles use chafers made of wire outside the carcass and organic fibers to improve the durability of the bead section. A structure is known in which the formed chafers are arranged along the carcass (for example, Patent Document 1).

JP, 2006-168500, A

By the way, in recent years, with the pursuit of improvement in vehicle performance and further improvement in efficiency, the ratio in which vehicles are used under severer environments than before, specifically, high load and high speed, is increasing.
Therefore, higher durability is also required for heavy load tires mounted on such vehicles.

In particular, when a high load is applied, the possibility of damage to the bead portion, specifically, the possibility of damaging the carcass around the bead portion increases. On the other hand, in order to inhibit other performances such as the follow-up performance of the suspension, it is desirable to suppress the increase in the weight of the tire as much as possible.

Then, this invention is made in view of such a condition, and it aims at provision of the tire for heavy load which can further improve the endurance of a bead part, controlling the increase in tire weight.

The heavy load tire (heavy load tire 10) according to an aspect of the present invention is folded back from the inner side in the tire width direction of the bead portion (the bead portion 60) including the bead core (bead core 61) and the bead portion in the tire width direction. A carcass (carcass 40) including a folded portion (folded portion 41) and a carcass main portion (carcass main portion 42) continuous with the folded portion and extending to the tread portion (tread portion 20); and at least a part of the bead portion And a covering chafer (chafer 100). The chafer is provided between the bead core and the carcass, and is formed by covering an organic fiber with a rubber member. A linear distance between a bead maximum inner position (bead maximum inner position 61p) which is the innermost position in the tire width direction of the bead core and a tire radial outer end (outer end 100a) of the chafer is L1. Assuming that the linear distance between the maximum inner position and the carcass maximum outer position (the carcass maximum outer position 40p), which is the outermost position of the carcass in the tire width direction, is L2.

Meet.

FIG. 1 is a partial cross-sectional view of the heavy load tire 10 along the tire width direction and the tire radial direction. FIG. 2 is a partially enlarged cross-sectional view of the heavy load tire 10 along the tire width direction and the tire radial direction. FIG. 3 is an enlarged cross-sectional view of the bead portion 60 along the tire width direction and the tire radial direction of the heavy load tire 10. As shown in FIG. FIG. 4 is a view showing a simulation example based on the endurance test results of the conventional example and the embodiment (heavy load tire 10). FIG. 5 is an enlarged cross-sectional view of a bead portion 60 according to a modification. FIG. 6 is an enlarged cross-sectional view of a bead portion 60 according to another modification.

Hereinafter, embodiments will be described based on the drawings. In addition, the same or similar reference numerals are given to the same functions or configurations, and the description thereof will be appropriately omitted.

(1) Overall Schematic Configuration of Pneumatic Tire FIG. 1 is a partial cross-sectional view of a heavy load tire 10 according to the present embodiment taken along the tire width direction and the tire radial direction.

As shown in FIG. 1, the heavy load tire 10 has a tread portion 20 and a tire side portion 30. In FIG. 1, only one side in the tire width direction is shown based on the tire equator line CL, but the same shape (symmetrical shape) is also the other side in the tire width direction based on the tire equator line CL. It is.

The heavy load tire 10 is, for example, a tire suitably used for a construction vehicle such as a dump truck traveling in a crushed stone / miner / dam site, an articulated dump, a wheel loader, or an industrial vehicle. That is, the heavy load tire 10 is a pneumatic tire mounted on a vehicle such as a construction vehicle and an industrial vehicle to which a high load is applied. The heavy load tire 10 assembled to the rim wheel (not shown) may be filled with a gas other than air (for example, nitrogen gas) or a small amount of liquid (for example, coolant).

The tread portion 20 is a portion in contact with the road surface. The tread portion 20 is actually formed with a pattern (not shown) according to the usage environment of the heavy load tire 10 and the type of vehicle to be mounted.

The tire side portion 30 continues to the tread portion 20 and is positioned inward of the tread portion 20 in the tire radial direction. Specifically, the tire side portion 30 is a region from the tire width direction outer end of the tread portion 20 to the upper end of the bead portion 60. The tire side portion 30 may be called a sidewall or the like.

The carcass 40 forms a framework of the heavy load tire 10. The carcass 40 is folded back from the inner side in the tire width direction of the bead portion 60 to the outer side in the tire width direction, and extends to the tread portion 20. The carcass 40 includes a folded portion 41 folded back from the inner side in the tire width direction of the bead portion 60 to the outer side in the tire width direction, and a carcass main portion 42 connected to the folded portion 41 and extending to the tread portion 20.

The outer end 40 e of the carcass 40 in the tire width direction extends to the vicinity of the tire maximum width position P on the surface of the tire side portion 30. However, the outer end 40 e is located more inward in the tire radial direction than the tire maximum width position P.

The carcass 40 is a radial structure having a carcass cord (not shown) arranged radially along the tire radial direction. However, the bias structure is not limited to the radial structure, and may be a bias structure in which the carcass cords are arranged to intersect in the tire radial direction.

The belt layer 50 is provided on the inner side in the tire radial direction of the tread portion 20. The belt layer 50 is constituted by a plurality of (for example, 4 to 6) cord-containing belts.

The bead portion 60 is located inward of the tire side portion 30 in the tire radial direction. The bead portion 60 contacts the rim portion of the rim wheel and is locked to the rim portion. The bead portion 60 is formed in an annular shape along the tire circumferential direction.

The chafer 80 covers at least a part of the bead portion 60. Specifically, the chafer 80 is provided on the outside of the carcass 40 and covers a part of the bead portion 60 along the carcass 40. The chafer 80 may be formed of a wire, or may be formed of an organic fiber as in the case of the chafer 100, but in the present embodiment, it is formed of nylon.

Similarly to the chafer 80, the chafer 100 also covers at least a portion of the bead portion 60.
The chafer 100 is provided between the bead core 61 and the carcass 40.

The chafer 100 is, for example, a sheet-like member formed by coating a plurality of organic fiber cords arranged in parallel with a rubber member. The chafer 100 is provided in an annular shape along the tire circumferential direction. As the organic fiber cord, aliphatic polyamide (nylon) is preferably used.

(2) Position of Chafer 100 FIG. 2 is a partially enlarged cross-sectional view of the heavy load tire 10 along the tire width direction and the tire radial direction. Specifically, FIG. 2 is an enlarged view of a portion radially inward of the tire maximum width position P of the heavy load tire 10.

As shown in FIG. 2, the bead portion 60 includes a bead core 61 and a bead filler 65. In the present embodiment, the cross-sectional shape of the bead core 61 is hexagonal. That is, the bead core 61 has a hexagonal shape in a cross-sectional view along the tire width direction and the tire radial direction.

The bead filler 65 is provided on the outer side of the bead core 61 in the tire radial direction. The bead filler 65 may be referred to as a stiffener.

The bead filler 65 is provided so as to fill the void portion of the carcass 40 which is turned back from the inner side in the tire width direction by the bead core 61 to the outer side in the tire width direction. The bead filler 65 is formed of a member such as rubber that is harder than the rubber forming the tire side portion 30.

As described above, the chafer 100 is provided between the bead core 61 and the carcass 40. Further, the chafer 100 satisfies the following size and positional relationship in the heavy load tire 10.

Specifically, the linear distance between the bead maximum inner side position 61p, which is the innermost position of the bead core 61 in the tire width direction, and the outer end 100a, which is the tire radial outer end of the chafer 100, is L1. Further, a linear distance between the bead maximum inside position 61p and the carcass maximum outside position 40p, which is the outermost position of the carcass body 42 in the tire width direction, is L2. The chafer 100 satisfies the relationship shown in (Expression 1).

In addition, the linear distance L1 and the linear distance L2 are based on the value measured in the tire 10 for heavy load which is not assembled | attached to a rim wheel and load is not loaded. Moreover, in the actual measurement, the heavy load tire 10 cut along the tire width direction and the tire radial direction may be used, but in this case, the heavy load tire 10 is self-supporting even if laid. Although it may be, it is based on the value measured for the part which the deformation | transformation by the contact with the ground etc. has not produced.

Furthermore, it is preferable that the chafer 100 satisfy the relationship shown in (Expression 2).

Further, in FIG. 2, for convenience of explanation, the straight line distance L1 and the straight line distance L2 are shown using the lead wire, but at the time of measurement, the straight line distance between the bead maximum inner position 61p and the outer end 100a and the bead maximum inner side The linear distance between the position 61p and the carcass maximum outside position 40p may be measured.

The outer end 100 a of the chafer 100 is offset from the outer end 65 a which is the tire radial direction outer end of the bead filler 65. That is, the position of the outer end 100a is different from the position of the outer end 65a in the tire radial direction.

(3) Structure of Bead Portion 60 FIG. 3 is an enlarged cross-sectional view of the bead portion 60 along the tire width direction and the tire radial direction of the heavy load tire 10.

As shown in FIG. 3, the inner end 100 b, which is the tire radial direction inner end of the chafer 100, extends to the tire radial direction inner side than the bead maximum inner position 61 p of the bead core 61.

As described above, the cross-sectional shape of the bead core 61 is hexagonal, and the bead maximum inner position 61p corresponds to one vertex of the hexagon. The inner end 100b extends to the inner side in the tire radial direction than the bead maximum inner position 61p, but the tire diameter than the apex 63 which is the apex of the bead core 61 (hexagon) inner to the tire radial direction than the bead maximum inner position 61p. End outside in direction.

Further, the inner end 100 b which is the tire radial direction inner end of the chafer 100 is positioned inward in the tire width direction than the core center line C 1 passing through the center of the bead core 61 and the central portion of the lower end.

An outer end 80 a, which is a tire radial direction outer end of the chafer 80, is positioned inward in the tire radial direction than the outer end 100 a of the chafer 100. In addition, an inner end 80b, which is the tire radial direction inner end of the chafer 80, is positioned outward in the tire width direction than the inner end 100b.

The tire radial inner end (inner end 80b, inner end 100b) means the end of the chafer in the tire radial direction, and does not necessarily mean the innermost position in the tire radial direction.

(4) Action / Effect Next, the action and effect of the heavy load tire 10 will be described. FIG. 4 shows a simulation example based on the endurance test results of the conventional example and the example (heavy load tire 10). Moreover, the method and conditions of a durability test, etc. are as follows.

・ Tire size: 59 / 80R63
・ Test method: Continuous operation with drum tester (repeated load input)
The conventional example is different from the heavy load tire 10 in the presence or absence of the chafer 100. Specifically, the heavy load tire 10 has a chafer 100, L1 is about 200 mm, and L2 is about 600 mm. On the other hand, the conventional example does not include the chafer 100.

As shown in FIG. 4, a load was repeatedly input to the heavy load tire to be tested, and the damage area of the carcass (damage width in the tire radial direction * damage width in the tire circumferential direction) was measured. In the conventional example, a certain damage area occurred 90 hours after the start of the test (the number of repetitive load inputs = about 200,000 times). On the other hand, in the example, the certain damage area occurred 330 hours after the start of the test (the number of repetitive load inputs = about 700,000 times).

Based on the results of this endurance test, set an estimated failure area where it is estimated that a CBU (Cord Breaking Up) where the cord (carcass code) that constitutes the carcass breaks will occur, and the number of repetitive load inputs until the CBU (time The simulation was performed for.

As a result, as shown in FIG. 4, in the example, it is expected that the durability (life) will be improved by about 35% over the conventional example.

That is, in the heavy load tire 10, the chafer 100 provided between the bead core 61 and the carcass 40 is disposed so as to satisfy the relationship of (Expression 1) described above. Therefore, the chafer 100 is positioned to cover the boundary between the bead core 61 and the bead filler 65. Therefore, even if separation of the bead core 61 and the bead filler 65 occurs due to repeated load input, the bead core It becomes difficult for the tire 61 to directly contact the carcass 40.

As a result of the separation between the bead core 61 and the bead filler 65 occurring in the CBU described above, the carcass 40 is scraped by the bead core 61 coming into contact with the carcass 40, and finally, the cord constituting the carcass 40 is judged (fatigue failure ) In order to

Moreover, since the chafer 100 is arrange | positioned so that the relationship of (Formula 1) may be satisfy | filled, the chafer 100 can be arrange | positioned only in a required and sufficient range, and the weight increase of the tire 10 for heavy loads can also be suppressed. Further, the amount of chafer 100 used can also be suppressed, which contributes to the suppression of the manufacturing cost of the heavy load tire 10.

That is, when (L1 / L2) exceeds (5/12), the size of the chafer 100 becomes larger than necessary, and the amount of chafer 100 used increases. The effect described above can be achieved by protecting the bead maximum inner position 61p, which is the innermost position of the bead core 61 in the tire width direction, by the chafer 100 while setting (L1 / L2) ≦ (5/12).

In addition, as described above, the chafer 100 preferably satisfies the relationship of (Expression 2). When (L1 / L2) is less than (1/24), the rigidity of the members constituting the chafer 100 is lowered, and separation and the like are easily generated by repetitive input to the vicinity of the bead portion 60.

As described above, according to the heavy load tire 10, the durability of the bead portion 60 can be further improved while suppressing an increase in the weight of the tire.

In the present embodiment, the inner end 100b of the chafer 100 extends to the inner side in the tire radial direction than the bead maximum inner position 61p. Therefore, it is possible to effectively prevent the carcass 40 from being scraped by the portion of the apex of the bead core 61 corresponding to the bead maximum inner position 61p coming into contact with the carcass 40. Thereby, the durability of the bead portion 60 can be further improved.

In the present embodiment, the outer end 100 a of the chafer 100 is offset from the outer end 65 a of the bead filler 65. Therefore, in the vicinity of the outer end 65 a of the bead filler 65, it is possible to prevent the occurrence of undesirable deformation and strain that may cause a failure. Thereby, the durability of the bead portion 60 can be further improved.

(5) Other Embodiments The contents of the present invention have been described above according to the examples, but the present invention is not limited to these descriptions, and various modifications and improvements are possible. It is obvious to the trader.

For example, the structure of the bead portion 60 may be changed as follows. FIG. 5 is an enlarged cross-sectional view of a bead portion 60 according to a modification.

As shown in FIG. 5, the cross-sectional shape of the bead core 61A is not hexagonal but circular. In this case, the bead maximum inner position 61p means the innermost position of the bead core 61A in the tire width direction. Here, the tire width direction may be a direction parallel to a straight line passing through the toe portion of the bead portion 60 and the heel portion.

Further, the arrangement position of the chafer 100 may be changed as follows. FIG. 6 is an enlarged cross-sectional view of a bead portion 60 according to another modification.

As shown in FIG. 6, as described above, the cross-sectional shape of the bead core 61 is hexagonal. Specifically, the bead core 61 has a hexagonal shape having a bottom surface 62 along the tire width direction on the inner side in the tire radial direction.

The chafer 100C is different from the chafer 100 in the position of the inner end 100b. Specifically, the inner end 100 b of the chafer 100 C extends to the end 62 e of the bottom surface 62 outside in the tire width direction.

Further, it is preferable that the inner end 100 b of the chafer 100 C extend to the inner side in the tire radial direction of the bead core 61 and be offset from the center of the bead core 61 in the tire width direction. For this reason, it can prevent that a rigid level | step difference generate | occur | produces in the center part in the tire width direction of the bead core 61 to which a high load is loaded. Thereby, the durability of the bead portion 60 can be further improved.

Furthermore, in the embodiment described above, the organic fiber cord constituting the chafer 100 is formed of an aliphatic polyamide (nylon), but may be formed of another organic fiber cord, for example, an aramid fiber.

Although the chafer 80 is provided in the embodiment described above, the chafer 80 may not be provided.

Although the heavy load tire 10 is described to be suitably used for construction vehicles, industrial vehicles, and the like in the embodiment described above, the heavy load tire 10 may be used as a truck and bus tire.

While the embodiments of the present invention have been described above, it should not be understood that the statements and drawings that form a part of this disclosure limit the present invention. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this disclosure.

The heavy load tire described above is useful because the durability of the bead portion can be further improved while suppressing an increase in the weight of the tire.

10 Heavy load tires 20 tread portion 30 tire side portion 40 carcass 40 p carcass maximum outer position 41 folded portion 42 carcass main portion 50 belt layer 60

bead portion

61, 61A bead core 61 p bead maximum inner position 62 bottom surface 62 e end portion 63 apex 65 bead filler 65a outer end 80 chafer 80a outer end 80b inner end 100, 100C chafer 100a outer end 100b inner end

Claims

A bead portion including a bead core,
A carcass including a folded portion folded back to the outside in the tire width direction from an inner side in the tire width direction of the bead portion, and a carcass main portion continuous with the folded portion and extending to the tread portion;
A heavy duty tire comprising: a chafer covering at least a part of the bead portion;
The chafer is provided between the bead core and the carcass, and is formed by covering an organic fiber with a rubber member,
A linear distance between a bead maximum inner position, which is the innermost position of the bead core in the tire width direction, and a tire radial outer end of the chafer is L1, a bead maximum inner position, and a tire width of the carcass main body Assuming that the linear distance from the carcass maximum outside position, which is the outermost position in the direction, is L2,

Heavy duty tire that meets
The heavy load tire according to claim 1, wherein the tire radial direction inner end of the chafer extends to the tire radial direction inner side than the bead maximum inner position.
The heavy load tire according to claim 1, wherein the tire radial direction inner end of the chafer extends to the tire radial direction inner side of the bead core and is offset from the center of the bead core in the tire width direction.
The bead core has a hexagonal shape having a bottom surface along the tire width direction on the inner side in the tire radial direction in a cross sectional view along the tire width direction and the tire radial direction,
2. The heavy load tire according to claim 1, wherein the tire radial direction inner end of the chafer extends to an end portion of the bottom surface in the tire width direction.
The bead portion has a bead filler provided on the tire radial direction outer side of the bead core,
The heavy load tire according to claim 1, wherein the tire radial direction outer end of the chafer is offset from the tire radial direction outer end of the bead filler.
The heavy duty tire according to claim 1, wherein the organic fiber is an aliphatic polyamide.